This research will seek to define the role of certain immunological phenomena in the establishment of experimental periodontal disease in gnotobiotic rats. The research plan has three major directions: (1) To determine if feeding a defined antigen to previously sensitized germfree rats will result in periodontal bone loss. (2) To characterize the gingival T and B cell response in germfree animals monoinfected with certain pathogenic organisms. (3) To determine the effects of induction of a specific salivary IgA antibody response on the establishment of periodontal bone loss in monoinfected gnotobiotic rats. A combination of immunological techniques will be employed in these investigations. Peripheral sensitization will be determined by lymphocyte transformation. T and B cells will be identified in intact gingival tissue and cell suspensions by specific fluoresceinated reagents. Serum and salivary antibody response will be determined by a radioactive antigen-binding technique. BIBLIOGRAPHIC REFERENCES: Taubman, M.A. and Smith, D.J., (1976). Immune components in dental plaque. J. Dent. Res. (Special Issue C) 55:C153-C162. Pulver, W.H., Taubman, M.A. and Smith, D.J. (1976). Immune components in normal and inflamed human dental pulp. Archs. Oral Biol. (In press).